If you have kids and wonder if all that time they spend on their smartphones endlessly scrolling, snapping and texting is affecting their brains, you might want to put down your own phone and pay attention. The federal government, through the National Institutes of Health, has launched the most ambitious study of adolescent brain development ever attempted. In part, scientists are trying to understand what no one currently does: how all that screen time impacts the physical structure of your kids' brains, as well as their emotional development and mental health.

At 21 sites across the country scientists have begun interviewing nine and ten-year-olds and scanning their brains. They'll follow more than 11,000 kids for a decade, and spend $300 million doing it. Dr. Gaya Dowling of the National Institutes of Health gave us a glimpse of what they've learned so far.

Dr. Gaya Dowling: The focus when we first started talking about doing this study was tobacco, marijuana, all drugs the screen time component really came into play because we were wondering what is the impact? I mean, clearly kids spend so much time on screens.

The first wave of data from brain scans of 4,500 participants is in and it has Dr. Dowling of the NIH and other scientists intrigued.

The MRI's found significant differences in the brains of some kids who use smartphones, tablets, and video games more than seven hours a day.

"We're sort of in the midst of a natural kind of uncontrolled experiment on the next generation of children."

Dr. Gaya Dowling: What we can say is that this is what the brains look like of kids who spend a lot of time on screens. And it's not just one pattern.

Anderson Cooper: That's fascinating.

Dr. Gaya Dowling: It's very fascinating.

The colors show differences in the nine and ten-year-olds' brains. The red color represents premature thinning of the cortex. That's the wrinkly outermost layer of the brain that processes information from the five senses.

Anderson Cooper: What is a thinning of the cortex mean?

Dr. Gaya Dowling: That's typically thought to be a maturational process. So what we would expect to see later is happening a little bit earlier.

Anderson Cooper: Should parents be concerned by that?

Dr. Gaya Dowling: We don't know if it's being caused by the screen time. We don't know yet if it's a bad thing. It won't be until we follow them over time that we will see if there are outcomes that are associated with the differences that we're seeing in this single snapshot.

The interviews and data from the NIH study have already revealed something else: kids who spend more than two hours a day on screens got lower scores on thinking and language tests.

Anderson Cooper: When the study is complete, is it possible that a researcher will be able to say whether or not screen time is actually addictive?

Dr. Gaya Dowling: We hope so. We'll be able to see not only how much time are they spending, how they perceive it impacting them, but also what are some of the outcomes. And that will get at the question of whether there's addiction or not.

Anderson Cooper: When will you have the answers that you're searching for?

Dr. Gaya Dowling: Some questions we'll be able to answer in a few years. But some of the really interesting questions about these long-term outcomes, we're gonna have to wait awhile because they need to happen.

That delay leaves researchers who study technology's impact on very small children anxious.

Dr. Dimitri Christakis: In many ways, the concern that investigators like I have is that we're sort of in the midst of a natural kind of uncontrolled experiment on the next generation of children.

Dr. Dimitri Christakis at Seattle Children's Hospital was the lead author of the American Academy of Pediatrics' most recent guidelines for screen time. They now recommend parents, "avoid digital media use, except video chatting, in children younger than 18 to 24 months."

Get the Smartphone out of the kids.

The American Academy of Pediatrics (AAP) and the Canadian Society of Pediatrics should not be exposed to electronic appliances from 0 to 2 years old, The 18-year-old announced that exposure should be limited to two hours a day. (AAP 2001/13, CPS 2010)

The following ten studies support this claim. Information on the results of the studies mentioned is listed in the zone's Fact Sheet on the zonein.ca site.